It is very important as a pilot to be able to decode weather information. The below text takes you through an actual weather report at LFPO airport called a METAR. METARs are updated every hour.

The items that are in red is the weather code that is being decrypted.

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
Observation made the 4th day of the current month at 1300 Z (UTC).

c) Wind

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
Wind blowing from 360° at 20 kt (knots)
Also available :
00000KT = wind calm
27010G25KT = 270° / 10 kt gusting 25 kt
VRB03KT = variable direction at 3 kt
36020KT 320V040 = average wind 360° / 20 kt, direction varying from 320° to 040°

---

d) Visibility:

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
Minimal visibility observed on a 360° round is 1200 m
Runway Visual Range (RVR) for runway 26 is 400 m
Also available :
4000 = 4 km
09SM = visibility in statutes miles
0000 = visibility less than 50 m
9999 = visibility higher than 10 km
4000NE = visibility 4000 m to the north-east (=> average visibility = 1.5x4000 = 6000)
1400S 4000N = visibility 1400 m to the south but 4000 m to the north
R25/M0075 = RVR runway 25 is less than 75 m
R33L/P1500 = RVR runway 33 left is higher than 1500 m
R16R/1000D = RVR runway 16 right is 1000 m, deterioration expected (D=Down)
R33C/0900N = RVR runway 33 central is 900 m, no change expected (N=No change)
R27/0150V0300U = RVR runway 27 is variable (V) from 150 to 300 m , improvement expected (U= Up)

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
Heavy rain shower
Also available :
As far intensity is concerned :
+ = heavy - = light nothing = moderate
As far as proximity is concerned :
VC = ViCinity (within 8 km)
As far as description is concerned :
BC = BanC - fog bench
BL = BLowing
DR = DRifting
FZ = FreeZing
MI = MInce - Thin fog layer
PR = Partial, partially
SH = SHower
TS = ThunderStorm
As far as precipitations are concerned :
DZ = DriZzle
GR = GRêle - Hail (diameter > 5 mm)
GS = GréSil - Hail (diameter < 5 mm)
IC = Ice Cristal
PL = ice PEllets
RA = RAin
SG = Snow Grains
SN = SNow
As far as other phenomenons are concerned :
BR = BRume - Mist (vis 1000 to 3000 m)
DU = DUst
FG = FoG (vis < 1000 m)
FU = FUmée - smoke (vis < 3000 m)
HZ = HaZe = dry mist (visi < 3000 m)
SA = SAnd
VA = Volcanic Ashes

DS = Dust Storm
FC = Funnel Clouds
PO = Dust spins
SQ = SQuall
SS = Sand Storm

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
Clouds are Tower Cumulus broken at 4000 ft.
Cloudiness :
FEW = few - 1 à 2 octas
SCT = scaterred - 3 à 4 octas
BKN = broken - 5 à 7 octas
OVC = overcast - 8 octas
Type of clouds (indicated in the following cases only) :
CB = cumulonimbus
TCU = towering cumulus or cumulus congestus
Also available :
SKC = Sky Clear (no clouds)
OVC/// = clouds covering the sky and which base is below aerodrome level
VV/// = sky unvisible
VV002 = vertical visibility is 200 ft
CAVOK = ceiling and visibility OK 
    CAVOK= vis>10km , no clouds below 5000 ft or minimum safe altitude and no significant weather - see e).
NSC = no significant clouds
    NSC= No CB, no cloud < 1500m/5000ft or below the highest minimum sector altitude, whichever is greater,
    & CAVOK or SKC not appropriate

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
Air temperature is 17°C, dew point is 15°C
The closest to the air temperature is the dew point, the higher is the risk of precipitation (simplified explanation)
Also available :
02/M01 = Air at 2°C, dew point at -1°C
M03/M05 = Air at -3°, dew point at -5°
Temperature can be indicated in °F (US METARs) - Nothing more is indicated, it is just obvious that 71° is certainly not a °C air temperature ;-))

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
QNH = 1015 hPa (hectopascals - 1 hPa = 1 mb - millibar)
Also available :
A2985 = Altimeter setting QNH 29.85 inHg

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
REcent ThunderStorm
Also available :
RERA = REcent RAin
RESN = REcent SNow
WS TKOF RWY 26 = WindShear when taking off runway 26
WS LDG RWY 26 = WindShear when landing runway 26

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
RVR deterioration
M stands for Mauvais (deterioration)
B stands for Bon (improvement)
0 = max wind speed
1 = average wind speed and direction
2 = RVR runway visual range
3 = clouds
4 = precipitations
7 = dust storm, sans storm or snow storm
8 = storm with or without precipitations
9 = squall

LFPO 041300 36020KT 1200 R26/0400 +RASH BKN040TCU 17/15 Q1015 RETS M2 26791299
Rwy 26, ice (7) covering 51 to 100% of runway surface (4), 12 mm thick, uncertain braking action (99).
1st and 2nd figures (here 26) = runway 26 or 26L
For right runways, add 50 : example => 26L coded as 26, 26R coded as 76
88 = all runways
3rd figure (here 7, ice) = type of deposit on the runway :
0 = runway clean and dry
1 = damp
2 = wet
3 = frost
4 = snow
5 = wet snow
6 = slush
7 = ice
8 = compacted snow
9 = snow drift
/ = unknown, snow removal in progress
4th figure (here 9, 51-100%) = percentage of runway surface covered :
1 = less than 10%
2 = 11 to 25%
5 = 26 to 50%
9 = 51 to 100%
/ = unknown, snow removal in progress
5th and 6th figures (here 12) = deposit thickness
00 = less than 1 millimeter
01 = 1 mm
02 = 2 mm
03 = 3 mm
...
12 = 12 mm
...
90 = 90 mm
92 = 10 cm
93 = 15 cm
94 = 20 cm
95 = 25 cm
96 = 30 cm
97 = 35 cm
98 = more than 40 cm
99 = runway not available (due to deposit or snow removal in progress)
// = unable to measure
7th and 8th figures (here 99) = braking action
01 to 90 = coefficient 0.01 to 0.90
or
95 = good
94 = medium to good
93 = medium
92 = medium to poor
91 = poor
99 = uncertain
// = unknown

BECMG AThhmm = BECoMinG AT (time in hours and minutes)
BECMG FMhhmm TLhhmm = BECoMinG From... TilL
TEMPO FMhhmm = TEMPOrary FroM
SNOCLO = Airfirld closed due to snow
26 CLRD = Runway 26 cleared, back to normal, available again